Empress Yang Xianrong (羊獻容) (died 322), formally (as honored by Han Zhao) Empress Xianwen (獻文皇后, literally "the wise and civil empress") was an empress -- uniquely in the history of China, for two different empires and two different emperors. Her first husband was Emperor Hui of Jin, and her second husband was Liu Yao of Han Zhao. Also unique was the fact that she was deposed four and restored four times as the empress of Jin (five, if one counts a brief usurpation by Sima Lun against her husband in 301).
As Emperor Hui continued to be a pawn of the princes during the War of the Eight Princes, Empress Yang herself appeared to have had little influence. She was, however, frequently used as an excuse for certain conspirators' actions, and during the span from 304 to 306 she was deposed four times and restored four times, often in conjunction with her husband's nephew Sima Qin (司馬覃)'s fortunes as crown prince. She was nearly killed after her fourth removal in 305, as Sima Yong, then holding Emperor Hui at Chang'an and leaving her in the capital Luoyang, became convinced that she was easily usable by his opponents as a rubber stamp, and so he ordered that she be forced to commit suicide. The governor of the capital region, Liu Tun (劉暾) offered a petition to save her life, which nearly cost him his own -- as Sima Yong ordered to have him arrested, and he was barely able to flee with his life. However, after Liu's intercession, for whatever reason, Sima Yong cancelled the order to have her forced to commit suicide.
In 306, as the War of the Eight Princes neared its end and Emperor Hui was allowed to return to Luoyang after Sima Yue the Prince of Donghai defeated Sima Yong, he welcomed Yang back as his empress. In early 307, however, he was poisoned to death. (Most historians believe that Sima Yue was behind the poisoning, but there is no conclusive evidence.) The recognized heir was Emperor Hui's brother, Sima Chi the crown prince, but Empress Yang, believing that she would not be honored as empress dowager if her brother-in-law inherited the throne, tried to have Sima Qin declared emperor; she was rebuffed by Sima Yue, however, and Crown Prince Chi succeeded to the throne as Emperor Huai. (Her attempt might have cost Prince Qin his life, as Sima Yue had him executed in 308.) Emperor Huai honored her with the title "Empress Hui," but not empress dowager.
Empress Yang's influence or lack thereof during Emperor Huai's reign was unclear, but since Emperor Huai himself did not have much power (with Sima Yue still holding onto much the power), it was not likely that Empress Yang had significant influence. After Sima Yue's death in 311, the Jin armies were in shambles and unable to protect Luoyang any further. Luoyang soon fell to Han Zhao's armies, led by the generals Huyan Yan (呼延晏), Wang Mi (王彌), Shi Le, and Liu Yao the Prince of Shi'an. Liu Yao burnt most of Luoyang and executed a large number of Jin officials, but did not kill Empress Yang; instead, he took her as his own wife.
Liu Yao greatly favored her, and she was involved in governmental matters. She died in 322. Her son Liu Xī would continue to be crown prince, but both Liu Yao and Liu Xī were killed by Shi Le's Later Zhao forces after Han Zhao fell to Later Zhao in 329.